Messages in this thread | | | Subject | Re: [PATCH] driver core / ACPI: Avoid device removal locking problems | From | Toshi Kani <> | Date | Wed, 28 Aug 2013 10:55:41 -0600 |
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On Wed, 2013-08-28 at 10:12 +0800, Gu Zheng wrote: > On 08/28/2013 05:38 AM, Toshi Kani wrote: : > >> > >> What about changing device_hotplug_lock and acpi_scan_lock to rwsem? like the > >> attached one(With a preliminary test, it also can make the splat go away).:) > > > > I am curious how msleep(10) & restart_syscall() work in the change > > below. Doesn't the msleep() make s_active held longer time, which can > > lead the thread holding device_hotplug_lock to wait it for deletion? > > Yes, but it can avoid busy waiting.
I know, but it's kinda unfortunate to sleep with s_active held in this situation. But I am fine with the 5ms Rafael used in this latest patchset since this is a rare case anyway.
> > Also, does restart_syscall() release s_active and reopen this file > > again? > > Sure, it just set a TIF_SIGPENDING flag and return an -ERESTARTNOINTR error, s_active/file > will be released/closed in the failed path. And when do_signal() catches the -ERESTARTNOINTR, > it will change the regs to restart the syscall.
I see. This is a clever functionality.
Thanks, -Toshi
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